Purification of crude wax oxidates



Dec. 28, 1954 J. w. NELSON PURIFICATION OF' CRUDE WAX OXIDATES FiledAug. 16, 1950 ATTORNEYS PURIFICATION OF CRUDE WAXOXIDATES John WalterNelson, Hammond, Ind., assignor to Sinclair Refining Company, New York,N. Y., a corporation of Maine Application August 16, 1950, Serial No.179,758

6 Claims. (Cl. 260-452) My invention relates to the purification, by adual solvent extraction procedure, of crude wax acid mixtures of highmolecular weight prepared by conversion of Cat-C55 microcrystalline waxunder controlled oxidation conditions. In particular, I have found thatthe microcrystalline wax acids can be obtained in a high degree ofpurity and in improved yields by extraction in two stages, tirst with apolar organic solvent, e. g. a lower aliphatic alcohol, and then with alight hydrocarbon naphtha fraction.

In my copending application, Serial No. 148,729, led March 9, 1950, nowabandoned, I havek disclosed new, useful high molecular weight organicacid compositions and a general method for their preparation, byconversion of Cali-C55 microcrystalline waxes under controlled oxidationconditions. The acid compositions are especially characterized bysaponitication numbers in the' range of about 100 to 500, their highcontent of fatty acid molecules having upwards of eighteen carbon atoms,and low solubility in water. Essentially, I have disclosed that the acidcompositions are prepared by oxidizing microcrystalline waxes having 34to 55 carbon atoms per molecule in the presence of a stoichiometricexcess of oxygen and about 0.1 to 4.0 per cent by` weight of anoxidation catalyst at a temperature in excess of about 100 C. for aperiod of time suficient to eifectzsubstantially complete conversionofthe waxes to acids.

The reaction mass essentially comprises a mixture ofv carboxylic acidsof high molecular weight contaminated with small quantities of organicand inorganic materialsv such as catalyst material, side reactionproducts, unreacted wax, and color bodies. I have disclosed in 'mycopending application Serial No. 157,177 tiled April 20, 1950, now U. S.Patent No. 2,610,974, that the acids may be obtained in purified form bywashing the crude' acid mixture free of inorganic materials with waterand/or an inorganic acid and then distilling the mixture to separate outthe higher acids. For example, the acid mixture may be washed with waterand hydrochloric acid and then subjected to flash or moleculardistillation.

But since the monocarboxylic acids I'prepare have considerably more thaneighteen carbon atoms per molecule and are characterized by extremelylow vapor pressures, it is diicult to purify them by distillation.Distillation in a Hash still or molecular still, such as the fallingfilm still, does produce satisfactory products but the yield is onlvabout 25 to 55 per cent, depending on the saponiiication value of thecrude oxidate. However, the cost is relatively high and operatingcapacity is limited. Further, the overhead products from suchdistillation procedures contain unreacted hydrocarbons such as wax andoxygenated products other than acids. This is because any givenaliphatic hydrocarbon boils lower than an oxygenated compound with thesame number and arrangement of carbon atoms or, expressed another way,addition of oxygen to the molecule in the acid preparation processincreases its boiling point. Thus inert hydrocarbon material cannot beseparated from the crude oxidate by distillation since a group of waxmolecules of one molecular weight will distill under the same conditionsof temperature and pressure as a group of acid molecules of lowermolecular weight.

In my application Serial No. 169,215, filed June `20, 1950, I havedisclosed an extraction procedure for purifying the crude wax acidreaction mixture which represents an improvement over distillation interms of higher saponilication number wax acids.

yield, better product color and reduced operating costs. According tothis process the microcrystalline -waxl acids of good purity can beobtained by-extracting the crude acid composition with an organicsolvent selected from the saturated hydrocarbons having three to twelvecarbon atoms per molecule under conditions whereby the ratio of solventto crude acid is in the range approximating 2:1 to 12:1 by weight andthe temperature and pressure are such as to maintain the solvent inliquid phase.

The C3 to C12 solvents have proved to be excellent ex traction agentsfor the crude oxidates, with yields varying between 32 and 70 per cent.However, the disadvantage in using such solvents is that they extractinert material, such as unreacted microcrystalline wax along with themonocarboxylic acids.

I have now found that product yields and purity are unexpectedlyimproved by first extracting the acid compositions with a polar organicsolvent, particularly at light oxygen-containing solvent such as a loweraliphatic alcohol, before extraction with the C3 to C12 organic solvent.I have found that it is important for high yields and to obtain awax-free oxidate that the polar extraction precede the naphthafractionation. The operating conditions are also important in bothstages of-treatment.

ing 6 :l to l0 :1. It is necessary'to maintain a temperature andpressure relationship to keep the solventl in liquid phase. Thus, inextracting the crude acid compositions to obtain maximum possible yieldand purity of acid product, the impure acids are contacted with a loweraliphatic alcohol such as ethanol, at a solvent toacid ratio of 6 :l to10 :l by weight. The mixture, thoroughly agitated, is heated to about140 to 175 F. in an exof to 200 F. The hydrocarbon solvent is added totheacids in a ratio in the range approximating 2:1 to 12:1-

by weight. The temperature is maintained at about 150 to 175 F. and thepressure regulated to keep the solvent in liquid phase. The mixture iscooled, a solvent fraction enriched in pure acids taken ot overhead andthe solventis removed. Advantageously, the pure acids are iinally washedwith water and a mineral acid, such as hydrochloric acid and the pureproduct so obtained is dried. The residue from the first extraction canbe worked up by retreatment to increase the yield of low Product yieldsas high as 97 per cent by weight on the charge material are obtained bymy two stage process.

I use a lower boiling, solvent to effect extraction. The lower aliphaticalcohols and light ketones, such as methyl ethyl ketone, are exemplary.Of the alcohol solvents, I particularly prefer ethanol and methanol. orthe alcohol employed can be in dilute aqueous form. For instance, percent ethanol in water is a satisfactory solvent. The amount of thesolvent used in my process is critical in effecting satisfactoryextraction of oxidate from inerts. I found that the mixture of acidsdisplays a surprising mutual solubility effect-one acid upon another andthe acids on the wax. As a result, it is necessary to add sufficientsolvent beyond that required for ordinary solution in order to overcomethis effect. n On the other hand, excessive dilution is undesirablesince the solvent then dissolves the wax, which is normally about 1 percent soluble unless solubilized by the carboxylic acids. Accordingly,the polar solvent is'added in amounts so that the ratio of solvent tooxidate conditions whereby the solvent is present in amount so` that notquite all the acids are dissolved.

The unreacted wax phase collects at the bottom of the extraction zoneand when thev temperature of the mix- Ptented Degas, 1,954

The polar solvent and crude acid are contacted: in a solvent-acid weightratio in the range approximat oxygen-containing organic polarv Alcoholmixtures may be usedv 'ageaasse ture is above the melting point of thewax, it is separated by withdrawal in the liquid phase."Orth'e'extraction mixture may be cold settled 'for separation of wax,i. e., cooled to below the melting point of the wax whereupon thewax'solidiies in the bottom of the extraction vessel. Infthis case, thehigher solvent layer willcontain'solid acids in slurry form as wellasdissolved'acids; 4Depending on acids treated, this mayresult in a3-phase' system, clear upper layer amber incolor, middle layercontaining suspended particles of oxidate and a lower mass ofcrystalline wax. Upon heating the mixture again to above the meltingpoint of the wax, without any agitation, the waxmay be drawn out of thebottom of the vessel, or the upper solvent-acid slurry can be pumped outof the vessel. It may be advisable to test a portion of this acidmixture for additional wax content by diluting itwith solvent inan'ordinary beaker and examining for wax precipitation. In fact, by anyof these procedures, the wax should be extracted again with solvent for'further purification although it may be recycled in such form to theoxidation reactor along with fresh Wax for acid production.

`The`extraction temperature must be below the critical temperature ofthe solvent used while it is necessary to employ a pressure suicient tomaintainthe solvent inl liquid phase at the selected temperature. Thusdepending upon the operating temperature", the extraction will-be eitherof liquid-liquid contact or liquid-solid', since the crude acids meltaround 125 to 135 F. Generally, the temperature employed may be in anyelevated'ra'nge` approximating about 70 to about 200 F. Advantageously,I prefer a temperature over about 140 F. so as to provide liquid-liquidcontact and thereby insure good contact between the materials in theextraction zone. At lower temperatures there is the additionaldisadvantage in 'that the solvent tends to lose some of its selectivity.In this regard temperatures between aboutf140 to 175 F. are particularlysatisfactory.

lfExtraction is carried out in a conventional extraction vessel underthe operating conditions selected. In particular, I prefer to use anextraction tower equipped with reflux' condenser so as to operate at amaximum possible extraction efficiency, that is, at higher temperaturesthereby insuring good contact. ArThe mixture of polar solventl and crudeacid, advantageously preheated, is pumped, into the extraction vessel.It is agitated at the selected reflux. temperature, e. g. 140 to 175 F.,to insure thorough dispersion, as for about fifteen to thirty minutesor'even more. The mixtureis cooled to about 100 F., or to atmospherictemperature, withoutfurther agitation; and the upper slurry layer ofsolvent and dissolvedand solid acids is separated from the lower solidwax layer. Or the mixture after agitation may be settled for two toeight hours at 140 to 160 F. and the layers then separated. In addition,one extraction may be made or the acid materialmay be subjected to aseries of extractions. The solvent is separated from the acid byconventional means,fsuch as by flash distillation.

Butane and normal pentane are exemplary solvents'for the hydrocarbon`fractionation step.` The solventghowever, may be of straight chainstructure or branched chain or cyclic. Mixtures of hydrocarbonsadvantageously are used, and the hydrocarbon solvent 'may' containarelatively small amount of unsaturates or aromatics, such as up toabout per cent by weighton the solvent composition used. Indeed,`suitable""refinery"cuts provide low cost sources of'these solventssuch` a's a naphtha lcut from a boiling' range of 80"- to 1v200" F. Thehydrocarbon solvent should be` usedl in''the"ratio of about 2:1 to 12:1by weight to the crude acids'l. "Separation is difficult when less thanabout 2:1 solvent-crude acid ratio is maintained while with a ratio ofvabout 12:1 yields are appreciably lower.'4 Within' this range, increases1n the ratio tend to result in lower 'yields of pure acids, althoughincreases in solvent producehigherlweightv acids of slightly bettercolor. Advantage'o'usly; the extraction is carried out at ratios ofhydrocarbonf'solvent to crude acid in the range of about 2:5 :1 to4:1,fby weight.

In selecting a hydrocarbon solvent for maximum yields, thehlghermolecular weight solvents are unusuallyl good for extracting the lightercrude acids while the reverse 1s also true, the lighter. solvents aremost suitable :for the heavier acid mixtures. Interms of the most simplecorrelation, Iconsiderv the Cs to Cs hydrocarbons in' the lightersolvent range and that such solvents are best "adapted t'"`crude" acid"mixtures having' 'sa'ponification numbers of 250 and less and that theCe to C12 hydrocarbons function best on crudes of about 250 and highersaponitication numbers. Optimum results are obtained by adjustment ofthe extraction temperature to the solvent employed and thereforeindirectly to the acids being extracted.V Thus the lighter solventswhich are more satisfactory/for the heavier acids, are employed atextraction temperatures ofabout 80 to 140 F. while the heaviersolvents,\for use on the lighter acids, should be employed at extractiontemperatures of about 125 to 200 F. For instance, propane or butane areespecially satisfactory for 200-225 saponitication number acids at about80 to 100 F. Cs to Cio solvents extract high yields of pure acids from300 to 325 saponication crudes at temperatures of 125 to 150 F. However,satisfactory yields of pure acids from crudes of varyingmolecularweights may be obtained where the solvent is employed atl itsmost favorable temperature although it is not-correlated to the crudeacid being extracted, such as a heavy solvent on a heavy acid at hightemperatures. But where neither'the solvent, extraction temperature orcrude are taken into consideration, as I have disclosed, yields andproductV color are not particularly satisfactory. For-instance,extraction of heavy acids with a heavy solvent, but at low temperaturesresults in poorly colored products.

'.Essentially, the naphtha fractionation is carried out by thoroughlymixing the solvent and crude acid material,- maintaining the mixture atthe desired extraction temperature, and' separating the impure matterwhich drops out of-solution. Precipitation of the impure bottoms ispromoted by cooling the mixture to room temperature or slightly higher,say to about 100 F. The acid-solvent portion is then distilled torecover the hydrocarbon solvent, such as by flash distillation underre-l duced pressure. The extraction is carried out under pressureconditions so that the hydrocarbon solvent remains in'liquid phase. Forinstance, when propane, butane and pentanearey employed as solvents atlow temperatures,pressures as high as 200 to 300 p. s. i. may beneeded.l One extraction may be made or the acid material -'may besubjected to a number of extractions tit) or passes withthey solvent.Although separation of the heavy Vimpure bottoms most advantageouslyshould depend on gravity, it is also possible, especially with lowsolvent-acidratios, to employ centrifugation. Preferably,

extraction is carried out in an extraction tower, which may be equippedfor high pressures and with reflux condensers where necessary. Aninternal cooling coil may be used to cool thefmixtures for betterseparation. The acidand` hydrocarbon solvent are initially heated andmixed in aseparate mixing vessel and then are charged toy the extractiontower for separation.

After extraction with the polar solvent, but prior to naphthaextraction, various molecular weight fractions of the 'acids can beseparated in substantially pure 'form from the polar solvent-oxidateYmixture by fractional crystallization. :This is readily accomplished bypartial evaporation of the-mixture to crystallize out the heavier acidyfractionswhich will solidify as the solvent concentration.becomess'uccessively weaker. The oxidate fracytions mixture..then lmaybe. separately passed to the naphtha extraction.

t Advantageously, the crude acid compositions may be additionallyvpurified by either simple washing in an aqueous medium or/ by a'combined water and mineral acid wash.v In this way inorganic impuritiessuch as catalyst material are' removed. Where the acid is washed bywater and a' mineral acid, such as hydrochloric acid,y

which I prefer to do,.I have found that the final yield of pure'acid isbest when the water-acid wash follows both solvent extraction stages',although good-color stable productsresult when the washing technique isperformed between the two extraction stages. For example, after finalextraction with the hydrocarbon solvent, water and hydrochloric acid areadded to the acid material recovered. The resulting mixture is stirredand permitted to settle. The acid-water layer which separates out risremoved. The product may be washed again as with Water alone, the waterremoved after another settling periodand the washed product blown withair to evaporate'any remaining water. The washed acids are thenageosgsso;

heated to .about 201)` :F. while air. 'blowirigphxHA order' to removeany residual: hydrochloric acid or water-:present Asalreadyrstated, theorderbf thezextractionxsteps is important..'Reversalo-f:theoperations,i. e. naphthaffrac'- tionation` rst, results.innsignicant reduction .in` yields. Further, lextracting withthepolar-solvent rsthas the advantage that' the `unreactedfwaxzis separatedfrom the oxidate .without `being Vcarriedt through the. entire opera*tion:` with.` resulting. increase" inoperating cost.` and. likelihood ofproduct contamination. Theaseparatedzwaxfmay be conveniently recycled .tr the` oxidationv process by which the-crude oxidateisrprepared.Removalofthe dibasic` acids land other oxygenated` products iinthelbottoms fromxthe -hydrocarbon extractionzis'also facilitated by thepresent` procedure.

Byrpurifying, thecrudefwaxfacid` composition in accordance with my:dualrextractionzprocedure, purified products of good lcolorcharacteristics, interms of light color and stability thereof, and inexcellent yields are obtained. Generally, the eoloraoftheextracted acidproduct rangeszfrom pale cream. to amber. Upon reaction totheLcor'responding.saltsby treatment with hot concentrated caustic, thefavorablecolorcharacteristics are retained `Furth`er,`thedualiextraction proceduregives exbottomsl 'wash alcohol t represented 5weight' per centend-- hada` saponication. numberof :83A and -an acidnumber" 45. Thusthe ttal'recovery was 97 percent,.37 per-cent'. of whichcould beconsidered contaminatedwamand 60' per cen-tmaterial having anaveragesaponication.number of 170. Thetheoretical saponicatiounumberofthe carboxylic acids in the original mixture was' 179. "The acidmixture of saponicationA number 170 was then extracted witha 1001-165oF.'naphthacut at 125 F. and theproductso obtained'washed with .wa-terand hydroO chloriciacid.

Example II Settlingv Extract Bottoms Alcohol RunNo.v Acid. .Wt. Ratio"Temp., Time, Yield, Wt.. Sap. Acid Sap. Acid F., Hrs. Percent No No. No.No.

6:1 16o 4., 25e "13a I17o so 6: 1 145 4 261 117 175 40 4 a. s a a a pp 26-1 148 iso munter-.- 27o 135 cellent yields of' the pure product.Whilethe -yield in the: conventional distillation procedure m-ay only-be as high as 55 per cent for intermediate saponication number crudes,(1170-250), aszhigh as 70 per centwherein the 40' have obtainedyieldsas' high as97 per cent-of'products 45 basedfon the original crudeacidproduct.

The following examples are intended to more'clearly illustrate thenature of "the: present extractionprocess.

Example I A crude wax Iacid mixture havingf a saponication In run number4 two extract products were obtained` (ppt. and ltrate) :by partialsolvent evaporation, cooling and filtering. TheV fractionsfwerethen-stabilized.

'Products treated in accordance with the foregoing procedure was thenextracted with C3 to-Ciz'saturated hydrocarbons-solvents (as naphthacuts.) under moderate pres-' sure in an extraction vessel equipped withan. agitator. The bottoms was allowed to`settle out and the pure extraction product was obtainedby distillation. When cer tain oftheextraction products obtained by ethanol extraction were treated withthe organic solvents the bottoms always had a higher saponication numberand acid number than the extract. The following' results illustrate theextraction of the polarsolvent extracted materials by such hydrocarbonsolvents.

q 1 t Extract Bottoms l n Ven Charge Stock- Alcohol Sap. vBoilingy gmgExtract Run No. No;A v`Range, u Fp" Yield, Sap' cid- Sap, Acid F Wr' No.N o. N o. No.

. 9Di140 105 77 231 114 145 90-140 80 9U 248 117 285 142 90430 85 60.191 92 ."273 103 number ofl 113, -an-acid-number of 76.v and containingabout 37 per cent inert-materialwas obtained byoxidizing to completeconversionCsrto Gssfmicrocrystallinewax` in the presence of a smallamount of a potassium permanganate catalyst. The crude product was trstsubjected to extraction with an aqueous solution of 95 per cent ethanol.The weight ratio of alcohol to acids was 6 to l. The mixture was heatedto a retlux temperature of 172 F. and stirred for 30 minutes. Aftercooling to 160 F. and settling for 4 hours, the two layers wereseparated. The lower layer upon stabilizing represented 20 weight percent. This material analyzed as having a saponication No. 33 and acidNo. 18. The extract was then diluted with alcohol to increase the weightratio, alcohol to acid, to 8:1. After settling at 160 F. for 4 hours,two layers were again separated. The lower layer was washed with alcoholand then stabilized. It represented 17 weight per cent and had asaponication number of 10 and acid number of 3. The extract, afterremoval of the alcohol, represented weight per cent of the original andhad a saponication number of 178 and acid number 82. The materialrecovered by evaporation of the second In addition to the saponicationand acid number analysis used fordetermining theeiiiciency of separationof the v'monocarboxylic acids from inert materials as shown in ExamplesI and II chromatographic adsorption on activated alumina and silica gelwas also employed.

The accompanying drawing illustrates a somewhat schematic ow diagram ofa continuous two stage extraction process according to my invention. Asis shown by the drawing the crude acid composition is initiallyextracted with an Ialcohol solvent in extraction zone 4 `and the acidextract so recovered is then separately processed with a Ca t0 C12solvent in zone 24.

According to the drawing, a crude wax acid mixture having a saponicationnumber of about 250 and oontaining about l0 per cent by weight ofcontamination material is charged to the system by line 1, preheated inheater 2 and passed -by line 3 into extraction zone 4. Ethanol, employedas the'rst extraction solvent and fed to the process by line 5, ispreheated in heater 6 and charged into the extraction zone by line 7.Extraction zone 4 is an extraction tower equipped with reux condenser 8,internal cooling coils 9, and agitator 10. The

The'rreux temperature of the tower is ma-inatiriecl at' about 175 F.fforfteen to thirty minutes while the mixture. is' thoroughly agitated bymeans of agitator 10.'

Sucient'pressure is provided so -that the solvent remains in'liquidphase. Agitation is stopped and the mixture is then adjusted to about145 F. by cooling coils 9. A lower wax layer forms during about fourhours of settling over which is a slurry containing principallyk thealoohol and acid extract. The wax portion is removed as a bottomsproduct by line 11. This wax product may be used for preparation ofadditional wax acid mixtures by the oxidation process or may be recycledby line 12 for additional extraction in tower 4 since it usuallycontainssmall amounts of' pure acids. The slurry layer containing theacids and solvent is taken off asoverhead by liney 13 and passed toilash zone 14, a flash drum, for removal of the solvent'from the acidportion. The separated solvent is recovered by line 15 and may berecycled tofthevmixing zone as desired or removed from the system bybleed line 16. The acids are removed from the ash` zone by line 17.However, the lower molecular weight wax acid fractions may beadvantageously separated from the solvent-oxidate mixture before furtherextraction by fractional crystallization in zone .46. This isaccomplished by passing the mixture by line 44 to evaporator 46 andpartial evaporatlngoff solvent-oxidate mixture is then passed to thenaphtha extraction by line 47. The recovered acids are removed throughline 45 by heating to above their melting point and are separatelypassed through the naphtha extraction operation.

The acid material so treated is then extracted with a C3 to C12unsaturated hydrocarbon solvent. This is accomplished by preheating thealcohol-extracted acids from line 17 in heater 18 and passing the heatedacid material by line 19 into a mixing vessel 20 equipped with amechanical stirrer, 21. A 100-140 F. boiling range naphtha cutcon-taining over 90 per cent C3 to Cs satura-ted hydrocarbons, employedas the solvent in the second stage,vis charged from line 22 to the samemixing vessel'20, being also preheated in heater 18. The heated acidfand solvent are thoroughly agitated in the vessel whereupon they arepassed by line 23to 'extraction zone.

24. Extraction zone 24 is an extraction tower equipped withl reuxcondenser 25 and internal cooling coil 26. The acid material andhydrocarbon solvent are introduced into the extraction tower in asolvent to acid ratio of about 3:1 by weight. The reilux temperature ofthe tower is maintained at about 100 to 125 P. during extraction andsufficient pressure provided so that the solvent is maintained in liquidphase. The mixture is then cooled to atmospheric temperature by coolingcoil 26. A light solvent fraction, containing principally the solventand acid extract is taken oi overhead by line 27 while a heavy product,made up of organic impurities and which may contain a small amount ofsolvent, isremoved as bottoms by line 28. .The overhead solvent fractionis then passed by line: 29 to ilash zone 30, a flash drum, for removalof the hydrocarbon solvent from the acid. VThe separated solvent isremoved by line 31 from the iiash drum and-may be recycled to the mixing-zone as desired or bled from the system by bleed line 32.

Advantageously, the pure acids so recovered are addi the solvent tocrystalliz'e out the heavier acid fractions. The remainingtionallyfwashedfand 'dried as shown. Thepure acidmaterial isfpassed byline 33t() washingivessel 34 equipped withgmechanical stirrer 35. Waterandhydrochloric acid are added tothe vessel by lines- 36 and 37,respectively.

" The resulting -mixtureisy stirredf'and then `permitted to settle.The'acid-water-layer which forms is removed by line 38. Then the mixtureis washed with water alone from line 36, the mixture agitated, vallowedto settle'- and the wash water removed by line 38. The washed product'is then passed by line 39 for drying in vessel 40. The acid is-blownwith air passed through by lines 41 and 42 and during the air blowingoperation it is heated to about 200 F. in order to'remove anyy residualwater or hydrochloric acid that might bepresent. The pure acid productso obtained is removed from the system byline 43.

The pure' acid product obtained has a saponification number ofl about225- andsubstantially all of 4the 10 per cent contaminating materialsare removed.

I claim:

1. In the purification of crude wax acid compositions characterized bysaponification numbers in the range of about to 500, high content offatty acids having upwards of18carbon atoms per molecule and obtainedbyoxidation of C34 to C55 microcrystalline wax,1the steps of extractingthe crude oxidate with a lower boiling oxygen-containing organic polarsolvent at a ratio of solvent to oxidate of between about 6:1 to 10:1 byweight and under conditions of `temperature and pressure whereby thesolvent is maintained in liquid phase, separating the extract phase,recovering the oxidate therefrom, extracting the polar solvent-extractedoxidate with a saturated hydrocarbon Solvent of the group containingthree to twelve carbon atoms per molecule at a ratio of solvent tooxidate between about 2:1 to 12:1 by weight and under conditionsA oftemperature and pressure whereby the solvent is maintained in liquidphase, washing the wax oxidate with wfaterand a mineral acid subsequentto an extraction step, and recovering the puried-wax'acids from thesolvent mixture.

2. A process according to claim v1 wherein theoxidate is washed vwithwater and hydrochloricl acid' after extraction with the organic polarsolvent.

3. A- process according to claim 1 wherein the polar extraction agentisa lower aliphatic alcohol.

4. A process according to claim 1 wherein'a plurality of polarextractions are carried out prior to hydrocarbon extraction. n

5. A process according to claim 1 whereinfthe polar solvent-oxidatemixture is subjected to partial evaporation for fractionalcrystallization of acid material into fractions of limited molecularweight ranges.

6. A process according to claim 1 wherein the oxidate is washed withwater and hydrochloric acid after extraction with the saturatedhydrocarbon solvent.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,885,199 Hellthaler et al. Nov. 1, 1932 1,909,295 Luther etal. May 16, 1933 1,987,208 Peukert Jan. 8, 1935 1,993,646 Burwell Mar.5, 1935 2,002,533 Forlich etal.V yMay 28, 1935 2,222,215 -Ewing a .'Nov.19, 1940 2,318,669 Carr May 11, 1943

1. IN THE PURIFICATION OF CRUDE WAX ACID COMPOSITIONS CHARACTERIZED BYSAPONIFICATION NUMBERS IN THE RANGE OF ABOUT 100 TO 500, HIGH CONTENT OFFATTY ACIDS HAVING UPWARDS OF 18 CARBON ATOMS PER MOLECULE AND OBTAINEDBY OXIDATION OF C34 TO C55 MICROCRYSTALLINE WAX, THE STEPS OF EXTRACTINGTHE CRUDE OXIDATE WITH A LOWER BOILING OXYGEN-CONTAINING ORGANIC POLARSOLVENT AT A RATIO OF SOLVENT TO OXIDATE OF BETWEEN ABOUT 6:1 TO 10:1 BYWEIGHT AND UNDER CONDITIONS OF TEMPARATURE AND PRESSURE WHEREBY THESOLVENT IS MAINTAINED IN LIQUID PHASE, SEPARATING THE EXTRACT PHASE,RECOVERING THE OXIDATE THEREFROM, EXTRACTING THE POLAR SOLVENT-EXTRACTEDOXIDATED WITH A SATURATED HYDROCARBON SOLVENT OF THE GROUP CONTAININGTHREE TO TWELVE CARBON ATOMS PER MOLECULE AT A RATIO OF SOLVENT TOOXIDATE BETWEEN ABOUT 2:1 TO 12:1 BY WEIGHT AND UNDER CONDITIONS OFTEMPERATURE AND PRESSURE WHEREBY THE SOLVENT IS MAINTAINED IN LIQUIDPHASE, WASHING THE WAX OXIDATE WITH WATER AND A MINERAL ACID SUBSEQUENTTO AN EXTRACTION STEP, AND RECOVERING THE PURIFIED WAX ACIDS FROM THESOLVENT MIXTURE.